A Review of Additive Manufacturing Techniques and Post-Processing for High-Temperature Titanium Alloys

Abstract

Owing to excellent high-temperature mechanical properties, i.e., high heat resistance, high strength, and high corrosion resistance, Ti alloys can be widely used as structural components, such as blades and wafers, in aero-engines. Due to the complex shapes, however, it is difficult to fabricate these components via traditional casting or plastic forming. It has been proved that additive manufacturing (AM) is an effective method of manufacturing such complex components. In this study, four main additive manufacturing processes for Ti alloy components were reviewed, including laser powder bed melting (SLM), electron beam powder bed melting (EBM), wire arc additive manufacturing (WAAM), and cold spraying additive manufacturing (CSAM). Meanwhile, the technological process and mechanical properties at high temperature were summarized. It is proposed that the additive manufacturing of titanium alloys follows a progressive path comprising four key developmental stages and research directions: investigating printing mechanisms, optimizing process parameters, in situ addition of trace elements, and layered material design. It is crucial to consider the development stage of each specific additive manufacturing process in order to select appropriate research directions. Moreover, the corresponding post-treatment was also analyzed to tailor the microstructure and high-temperature mechanical properties of AMed Ti alloys. Thereafter, to improve the mechanical properties of the product, it is necessary to match the post-treatment method with an appropriate additive manufacturing process. The additive manufacturing and the following post-treatment are expected to gradually meet the high-temperature mechanical requirements of all kinds of high-temperature structural components of Ti alloys.

Hot Deformation Behavior and Microstructure Evolution Mechanisms of Ti6Al4V Alloy under Hot Stamping Conditions

“…To describe the flow behavior of materials at high temperatures, Zener et al [27] investigated the effects of temperature and strain rate on deformation to obtain Equation (1), and a further calculation able to produce Equation (2). In recent studies, the Arrhenius constitutive model has been widely used to describe the flow behavior of Ti6Al4V alloys at high temperatures.…”

“…In recent years, titanium alloys have been widely used in the aerospace and transportation industries, attributed to their high specific strength and corrosion resistance [ 1 , 2 ]. The application of titanium alloy products in major transportation vehicles like airplanes and trains reduces both self-weight and the frequency of component replacement [ 3 , 4 ], driving an increasing demand for titanium alloy machining processes characterized by low manufacturing costs, short machining cycles, and high forming quality.…”

Development of Bioactive Scaffolds for Orthopedic Applications by Designing Additively Manufactured Titanium Porous Structures: A Critical Review

“…At high cooling rates, depending on the class of a Ti alloy, a structure from a quasi-equilibrium Widmanstett structure consisting of α-phase plate packets [57] to a non-equilibrium fine-dispersed acicular martensite structure [58] with a high density of dislocations and twins [59] can be formed out of β-phase grains. The formation of such non-equilibrium structures leads to a significant increase in the strength and a loss in ductility of printed Ti alloys compared to those produced by traditional methods of metal forming [60,61]. In order to compensate for the effect of AM-induced microstructural features, specified heat treatments in the form of tempering or aging are applied [62,63].…”

Enhancing high-speed CNC milling performance of Ti6Al4V alloy through the application of ZnO-Ag hybrid nanofluids

“…In this context, challenging-to-machine materials like titanium alloys and nickel alloys have emerged as indispensable choices for key aerospace components [3]. Titanium alloys, renowned for their high specific strength, heat resistance, temperature stability, and corrosion resistance, have been in use since the 1950s [4]. However, their poor machinability poses a significant challenge, such as poor surface finish, high tool wear, high cutting forces, deformation at tool faces, thermal stresses, etc, due to limited thermal conductivity and unique elastic properties [5].…”